My plan, hopefully the experienced guru's here will tell me where I've gone astray....
The truck is a 1970 GMC SWB 1/2 ton with rear leafs. Bone stock, unmolested. 12 bolt rear with 3.73's. Purchased running with a badly neglected Rochester "BV" that somebody swapped in place of the "MV" that is supposed to be there. A freshly remanned by "Tomco" Rochester "MV"(1bbl) has just arrived.
Trying to do everything on the cheap, as much as possible...(Please offer your opinions on the following)
1) Replace old Saginaw three speed with 700r4.
2) Install pertronix, or GM stock HEI dizzy
3) Install set of PACESETTER headers(anyone have experience? Or offer alternatives?)
4) A simple glasspack muffler with 2.5" pipe
5) 31x10.5 rubber on 15x8 alloys
BTW, I will be adding power steering, and A/C, I know this is counterproductive to adding fuel economy, but most of my driving is in town, and I live in south Florida.

Will I need to add hot water heat to the bottom of the intake if I go the header route? The headers are just under $200.00, the heat plate another $30.00. The stock exhaust intake is about $150.00 new aftermarket. (the old one is FUBAR, cracked, etc.) Will I accomplish significantly more fuel economy to offset the extra $100.00 cost?
If you were building for max MPG, what would you do that I havent thought of here?
Again I appreciate all input, if I'm wasting time and $$, please let me know. TIA

Make sure you use a lock up type converter.
Get an advance kit for the dizzy.
Headers,,with small primary tubes,, or use the two cast iron ones from a member here.
If you want mileage,use a smaller & lighter rim & tire combo.

Main thing to get better gas mileage than stock,do not use the factory timeing settings,go more advanced,but emmisions will go up.

Next take out all the stuff in your truck that is not needed to reduce weight.
Four wheel alighnment.
Minimum toe in.

Mill the head to bump up compression.

Check you cranking compression to see if engine is in good shape along w/a leak down rate on each cylinder.

Pretty hot in south Florida?
Heated intake might not be necessary.
BTW,what is the difference w/a BV & MV carb?

MBHD

Run the inflation up to the highest pressure that you can still tolerate the ride. Just don't exceed the cold inflation limit on the sidewall.

For economy, lower it (not gonna help in town though).

Your kind of hamstrung with the truck though, lighter vehicles will get you better economy.

A good 3 angle valve job will be worth doing once you have the head off. Cleaning up the exhaust pocket under the exhaust valve a bit to get rid of the sharp edges will help too - just don't remove a lot of metal.

With the 700r4 installed the next step thats more $$ and you have to determine how much you want to spend on mod's vs gas at the pump is TBI.